高温及水稻类型对灰飞虱种群的影响

近年来,灰飞虱Laodelphax striatellus(Fall n)在江浙等地呈明显上升态势。采用不同温度及水稻类型处理灰飞虱若虫,获得灰飞虱种群在不同处理组合下的存活率、发育进度及抗寒力。结果表明,35℃的高温下,灰飞虱各龄若虫无论在杂交籼稻还是粳稻上,其发育进度均比25~30℃推迟2~7d。35℃高温下若虫死亡率较高,并且不能正常羽化。粳稻上饲养的灰飞虱若虫的存活率明显高于杂交籼稻,但水稻类型和温度对灰飞虱存活率的影响不存在明显的互作作用。在适宜温度下(27~30℃)用杂交籼稻饲养的灰飞虱,其过冷却点及结冰点均要比在高温(35℃)或低温(25℃)下饲养的低。在26~30.5℃变温条件下,杂交籼稻上饲养的灰飞虱的过冷却点和结冰点显著低于粳稻上饲养的,而且不同温度和水稻类型上的灰飞虱的过冷却点均低于零下10℃。可见江浙稻区冬季低温对灰飞虱的越冬已不存在制约作用。温度和水稻类型的变化是近年灰飞虱暴发成灾的重要原因。

Effects of rice type and temperature on the population of the rice small brown planthopper, Laodelphax striatellus

The occurrence trend of the small brown planthopper Laodelphax striatellus(Falln) (SBPH) in Jiangsu and Zhejiang Province was ascending in recent years. The effects of temperature and rice type on survival, fitness and cold tolerance of SBPH were studied in the present study. The results showed that the development of SBPH was retarded significantly under the 35℃ high temperature, and compared with 25～30℃ conditions, the developmental duration at the 35℃ delayed two to seven days. The mortality of nymph increased significantly at the 35℃ higher temperature, and the emerged adults were not found. The survival of the nymph reared on the japonica rice was significantly higher than that of the nymph on the indica hybrid rice. But there was no interactive effect between the temperature and rice type to survival of SBPH. The super-cooling point (SCP) and ice point (IP) of the 4～5th instar nymphae reared under the suitable conditions were significantly lower than that of the nymphae under the higher or lower temperature conditions. The SCP and IP of 4～5th instars nymphae reared on the indica hybrid rice were significantly lower than that on the japonica rice at the varied temperature (26～30.5℃). Moreover, all the SCPs of the 4～5th star nymphae reared on the indica hybrid rice and japonica rice were below -10℃, and the SBPH population would not be influenced by the low temperatures of winter in Jiangsu and Zhejiang. Therefore, it inferred that the variation of the air temperature and rice type would play key role in the outbreak of the SBPH population in recent years.